Subject: Re: bug#52835: [PATCH 0/2] Fix spawning a child not setting standard fds properly

From: Ludovic Courtès <[email-masked]>
Date: Sun, 25 Dec 2022 17:58:02 +0100

Hi Josselin,

Josselin Poiret <[email-masked]> skribis:

> I've added a convenience module (ice-9 spawn) with a `spawn` procedure
> in it, which takes an optional argument list which defaults to just the
> executable, and optional environment variables as well as in, out and
> err ports.  I also think everything in (ice-9 popen) should be migrated
> on the next major release, as well as being re-implemented in terms of
> `spawn` purely, so that the change is immediately noticeable.

OK.

> We're reaching the bike-shedding time now, but IMHO having such a
> `spawn*` exposed to the user seems fine, it's a pretty simple "raw"
> interface with fdes, and there is a convenience `spawn` function that is
> nicer for users.

‘spawn*’ is expressive enough, but a procedure with 6 positional
arguments cannot be exposed as-is IMO.

One tiny thing that’s missing is a boolean to choose between
‘posix_spawn’ and ‘posix_spawnp’.

So we need either ‘spawn’ defined in Scheme as you did, or directly use
‘scm_c_bind_keyword_arguments’ right in ‘scm_spawn_process’ (info
"(guile) Keyword Procedures"), to avoid ending up with two procedures.
I’m fine either way.

> Do we need to add a documentation page as well?

Yes, please.  :-)  I realize I’m asking a lot of things, so let me know
if you’d like to share the workload somehow.

Doc could go in the “Processes” section, or possibly in a new section
we’d add right after it, “Spawning Programs”.  We should probably add a
“@quotation Note” in the doc of ‘primitive-fork’ that briefly explains
why people should probably use ‘spawn’ rather than fork + exec.

Some cosmetic suggestions follow…

Thanks,
Ludo’.